Adult Swim and Valve are Teaming Up, offering signups for a newsletter, and saying they will announce something about Team Fortress 2 and the network next week. As for the Pyro, he seems to be holding back for now. Here's the announcement of the announcement:

COMING NEXT WEEK ADULT SWIM & VALVE ARE TEAMING UP FOR SOMETHING THAT YOU'LL PROBABLY ENJOY. TO LEARN HOW THEIR VIDEO GAME PEANUT BUTTER WILL BE GETTING IN OUR NETWORK'S CHOCOLATE, COME BACK NEXT WEEK.